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applications are inevitable. Moreover, the
availability of cloud-based services cannot be fully
guaranteed, forcing service consumers to build in
redundancy into their applications, so that alternative
services can be substituted when required in order to
maintain service continuity.
Service evolution has been the subject of recent
research interest, but most of the research on this
topic deals with service evolution from the service
provider perspective. We have argued that there is
an equal need to consider this problem from the
perspective of service consumers and develop
effective methods to protect service consumer
applications from changes in external services. In
this paper we describe an initial proposal for Service
Consumer Framework that attempts to address this
problem by providing resilience for consumer
applications to changes to external services as these
are evolved or become temporarily unavailable. The
basic idea of the framework involves the use of
service adaptors in combination with a service router
that re-directs requests to different service providers
based on their availability at runtime. Service
adaptors ensure that consumer applications can use
services that are currently supported by service
providers, and that the timing of upgrades to new
service versions is determined by the service
consumers, rather than dictated by service providers.
Using this framework, application designers can
choose from a number of services that provide
identical functionality (e.g. payment services) and
define the sequence of service execution to optimize
the cost and performance of the applications.
We have implemented prototype versions of
several service adaptors, and we are currently
working on the implementation of service repository
and service router using Microsoft .NET
technologies. Our current efforts focus on
developing a proof-of-concept prototype of the SCF
framework and on developing additional adaptors.
We will use this prototype to further refine the
design of the framework.
ACKNOWLEDGEMENTS
Authors wish to acknowledge support of GAČR
(Grant Agency, Czech Republic) grant No.
P403/11/0574 and ARC (Australian Research
Council) Grant Design of Service Interfaces
(2004000242).
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